I ended up buying a pair of tickets, rather than the one I needed, as they were darn good seats (Row O stalls, middle aisle). This means I now have one spare ticket, going for the price I bought it for (£51.09 including Recorded Delivery postage).

Anyone want a Row O Stalls ticket, seat 34 (3 seats from the centre aisle)? I'm afraid this means you'll be sitting next to little old me, but I promise to behave myself!